Methods and apparatus to perform load measurements on hinged devices

ABSTRACT

An example hinged device flexible substrate testing system includes: a first plate comprising a first surface configured to hold stationary a first side of a hinged device under test; a second plate comprising a second surface configured to hold a second side of the hinged device under test; a first cam follower coupled to the second plate; a first drive arm configured to move the first cam follower to cause the second plate to rotate about a hinge pivot axis of the hinged device under test; an actuator configured to rotate the drive arm; and a load cell configured to measure loads on the first plate while the actuator moves the second plate.

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 63/018,130, filed Apr. 30, 2020, entitled “METHODSAND APPARATUS TO PERFORM LOAD MEASUREMENTS ON HINGED DEVICES.” Theentirety of U.S. Provisional Patent Application Ser. No. 63/018,130 isexpressly incorporated herein by reference.

BACKGROUND

This disclosure relates generally to materials testing, and moreparticularly, to methods and apparatus to perform load measurements onflexible substrates.

Reliability testing for an assembly, or moving components of anassembly, may involve repetitively performing intended and/or unintendedmovements of the components to verify that the components and/orassembly reliably operates for a defined minimum number of cycles of themovements. For example, reliability testing of a flexible substrate mayinvolve repeatedly flexing the substrate in one or more ways, whiletesting for continued operation of the device and/or monitoring variousmodes of failure.

SUMMARY

Methods and apparatus to perform load measurements on hinged devices aredisclosed, substantially as illustrated by and described in connectionwith at least one of the figures, as set forth more completely in theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of an example hinged device test system toperform mechanical property testing on a hinged device, in accordancewith aspects of this disclosure.

FIG. 2 is a block diagram of an example implementation of the hingeddevice test system of FIG. 1 .

FIG. 3 is a perspective view of an example implementation of the hingeddevice test system of FIG. 1 .

FIG. 4A is a front elevation view of the example hinged device testsystem of FIG. 3 in which the hinged device is in an opened or unfoldedposition.

FIG. 4B is a front elevation view of the example hinged device testsystem of FIG. 3 in which the hinged device is in a closed or foldedposition.

FIG. 5 is a more detailed view of the example first plate, the flexures,and the load cell.

FIG. 6 is a side elevation view of the example hinged device test systemof FIG. 3 .

FIG. 7 is a plan view of the example hinged device test system of FIG. 3.

FIG. 8 illustrates a partially exploded view of another exampleimplementation of the translation linkage of FIG. 1 .

The figures are not necessarily to scale. Wherever appropriate, similaror identical reference numerals are used to refer to similar oridentical components.

DETAILED DESCRIPTION

Flexible specimens often include assemblies and/or devices that haveconstraint mechanisms, such as simple hinges, double hinges, ellipticalmechanisms, and/or other forms of constraints. Conventional measurementsystems are not capable of characterizing forces associated withflexible specimens that involve such constraint mechanisms, becauseconventional measurement systems are not able to fold such specimenswithout over-constraining the specimens (resulting in damage), and/orbecause the reaction forces produced by the constraint mechanisms aretypically many orders of magnitude greater than the reaction forcesproduced by the flexible material specimen.

Disclosed example hinged device testing systems provide repetitivestress testing and/or load measurement for hinged devices, whilereducing or minimizing additional stress induced on the hinged device bythe hinged device testing system itself. For example, some disclosedhinged device testing systems allow the specimen to be folded by thesystem while allowing the constraint device(s) of the specimen (e.g.,hinge(s)) to determine the exact folding path of the specimen, therebytesting the specimen in the same manner as in the eventual intended useof the specimen.

Some disclosed hinged device testing systems include fixturing thatprovides repetitive folding and unfolding of a hinged device, such as ahinged mobile electronic device (e.g., a smartphone). In some examples,the testing systems are configured such that the hinge of the hingeddevice controls a folding and unfolding path of a foldable substrate,while forces on the foldable substrate are measured. Disclosed examplesconfigure the fixturing, such as guiding of the moving parts, such thatthe fixturing does not create additional force on the hinge(s) of thehinged device as the sides of the hinged device are folded together orunfolded.

In some examples, the hinged device testing systems include atranslation linkage to limit forces on the device that are not in thedirection measured using the hinged device testing system. As anexample, a translation linkage may translate lateral forces on themeasured side(s) of the hinged device to forces in the direction ofmeasurement (e.g., forces normal to a face of the hinged device, forcesassociated with resistance of the hinge to folding, etc.).

Disclosed examples of the hinged device testing systems include adynamic, or moving, portion, and a stationary, load measuring portion.Examples of the dynamic portion include a rotary shaft which articulatesmultiple drive arms. The drive arms each feature a slot in which a camfollower (e.g., a bearing) is free to travel radially along the drivearm. The bearings are each secured to a shared mounting plate that movesa portion of a hinged device that is attached to the mounting plate. Thestationary, load measurement portion is affixed to a same base plate asthe dynamic side. The stationary side features a static stationarymounting plate to which another portion of the hinged device isattached. In some examples, the stationary mounting plate is suspendedabove the base plate using parallel flexures. In addition to theparallel flexures, a load cell (e.g., including corresponding adaptercomponents) connect the stationary mounting plate to the base plate.

In some examples, the stationary side also includes rigid mountingpoints, which are decoupled from the load measurement path, to whichportions of the hinges may be attached to reduce or eliminate the forcesof the hinges. By providing rigid mounting points for the constraintmechanisms of the specimen, disclosed examples are capable of highlysensitive measurements of the folding forces of the specimen because thereaction forces associated with the constraint mechanism are isolatedfrom the load measurement.

Disclosed example hinged device testing systems are sufficientlyversatile to accommodate a variety of constraint mechanisms, includinghinges, double hinges, and mechanisms not yet contrived. Disclosedexamples can accommodate different specimen sizes with little or noadjustment (e.g. 2 mm bends, 3 mm bends, etc.). Disclosed examples arecapable of expansion to test multiple specimens at once by connectingthe specimens to the same driveshaft. Furthermore, disclosed exampletesting systems are inexpensive.

FIG. 1 is a block diagram of an example hinged device test system 100 toperform mechanical property testing on a hinged device 102. The examplehinged device 102 may be an electronic or other device having one ormore hinges 104 allowing at least a first portion 106 and a secondportion 108 of the hinged device 102 to at least partially fold. Thesystem 100 of FIG. 1 is configured to repeatedly fold and unfold thehinged device 102 to measure forces associated with the folding andunfolding (e.g., resistive forces, spring forces, etc.). FIG. 1illustrates the hinged device 102 in an unfolded or flat position (solidline) and folded position (dotted line).

The example system 100 includes a first plate 110, a second plate 112,one or more cam followers 114 coupled to the second plate 112, one ormore drive arms 116, an actuator 118, one or more load cells 120, and atranslation linkage 122. The system 100 may include additional features,such as structural support or framing, processing circuitry,communications and/or input/output (I/O) circuitry, and/or any othercomponents.

The first plate 110 has a first surface 124 to which the first side 106of the hinged device 102 is attached or affixed, and held stationarywith respect to the first surface 124. The second plate 112 has a secondsurface 126 to which the second side 108 of the hinged device 102 isattached or affixed, and held stationary with respect to the secondsurface 126. The plates 110, 112 are separated by a gap, which isbridged by the hinge 104.

The drive arm(s) 116 move the corresponding cam follower(s) 114 to causethe second plate 108 to rotate about a pivot axis of the hinge 104 ofthe hinged device 102. The actuator 118 rotates the drive arm(s) 116 tocause the second plate 112 to move the second portion 108 of the hingeddevice 102 from the first position (shown in solid lines) toward thefirst portion 106 in the folded position (shown in broken lines). Thedrive arm(s) 116 allow motion of the cam follower(s) 114 along thelength of the drive arm(s) 116 so that the system 100 limits oreliminates force on the first portion 106 of the hinged device 102 bythe weight of the second plate 112 or the drive arm(s) 116, such thatthe measured force on the first portion 106 of the hinged device 102 iscompletely determined by the actuation of the hinge 104.

In some examples, the actuator 118 may be a motor attached to the drivearm(s) 116 to rotate the drive arm(s) 116 about a pivot of the drivearm(s) 116.

The load cell 120 measures loads on the first plate 110 while theactuator 118 moves the second plate 112. In particular, the load cell120 measures stress (e.g., folding force) on the hinged device 102 asthe hinged device 102 is folded by measuring load exerted by the firstside 106 of the hinged device 102 onto the first plate 110.

The translation linkage 122 limits movement of the first plate 110 indirections other than the direction in which the load cell 120 is loadedby the first plate 110. For example, if the load cell 120 is configuredto measure loads in a direction perpendicular to the plane of the firstsurface 122, the translation linkage 122 limits movement of the firstplate 110 in directions parallel to the plane of the first surface 124while permitting load to be transferred from the first plate 110 to theload cell 120. An example translation linkage 122 may include one ormore four-bar linkages coupled to a frame that is fixed with respect tothe load cell 120. In some examples, the translation linkage 122 isfurther limited in a direction toward the load cell 120 to preventoverloading of the load cell 120. For example, a stopping point may beattached to the frame to prevent movement of the four-bar linkage(s) andthe first plate 110 toward the load cell 120 beyond the stopping point.

In operation, the example load cell 120 may be biased or offset aftersecuring the hinged device 102 to the first plate 110 and the secondplate 112 to subtract a preload from the test measurements. For example,the preload on the load cell 120 may occur due to the weight of thefirst plate 110, the weight of translation linkage 122, and/or theweight of the first side 106 and/or the hinge 104 of the hinged device102 on the first plate 110. By determining the preload on the load cell120, the load cell 120 can be calibrated or offset to measure the stresson the hinged device 102 during folding and unfolding.

FIG. 2 is a block diagram of an example implementation of the hingeddevice test system 100 of FIG. 1 . As illustrated in FIG. 2 , the hingeddevice test system 100 includes a test fixture 201 and a computingdevice 202.

The example computing device 202 may be a general-purpose computer, alaptop computer, a tablet computer, a mobile device, a server, anall-in-one computer, and/or any other type of computing device. Thecomputing device 202 of FIG. 2 includes a processor 203, which may be ageneral-purpose central processing unit (CPU). In some examples, theprocessor 203 may include one or more specialized processing units, suchas FPGA, RISC processors with an ARM core, graphic processing units,digital signal processors, and/or system-on-chips (SoC). The processor203 executes machine-readable instructions 204 that may be storedlocally at the processor (e.g., in an included cache or SoC), in arandom access memory 206 (or other volatile memory), in a read-onlymemory 208 (or other non-volatile memory such as FLASH memory), and/orin a mass storage device 210. The example mass storage device 210 may bea hard drive, a solid-state storage drive, a hybrid drive, a RAID array,and/or any other mass data storage device. A bus 212 enablescommunications between the processor 203, the RAM 206, the ROM 208, themass storage device 210, a network interface 214, and/or an input/outputinterface 216.

An example network interface 214 includes hardware, firmware, and/orsoftware to connect the computing device 201 to a communications network218 such as the Internet. For example, the network interface 214 mayinclude IEEE 202.X-compliant wireless and/or wired communicationshardware for transmitting and/or receiving communications.

An example I/O interface 216 of FIG. 2 includes hardware, firmware,and/or software to connect one or more input/output devices 220 to theprocessor 203 for providing input to the processor 203 and/or providingoutput from the processor 203. For example, the I/O interface 216 mayinclude a graphics-processing unit for interfacing with a displaydevice, a universal serial bus port for interfacing with one or moreUSB-compliant devices, a FireWire, a field bus, and/or any other type ofinterface. The example extensometer system 10 includes a display device224 (e.g., an LCD screen) coupled to the I/O interface 216. Otherexample I/O device(s) 220 may include a keyboard, a keypad, a mouse, atrackball, a pointing device, a microphone, an audio speaker, a displaydevice, an optical media drive, a multi-touch touch screen, a gesturerecognition interface, a magnetic media drive, and/or any other type ofinput and/or output device.

The computing device 202 may access a non-transitory machine-readablemedium 222 via the I/O interface 216 and/or the I/O device(s) 220.Examples of the machine-readable medium 222 of FIG. 8 include opticaldiscs (e.g., compact discs (CDs), digital versatile/video discs (DVDs),Blu-ray discs, etc.), magnetic media (e.g., floppy disks), portablestorage media (e.g., portable flash drives, secure digital (SD) cards,etc.), and/or any other type of removable and/or installedmachine-readable media.

The test fixture 201 is coupled to the computing device 202. In theexample of FIG. 2 , the test fixture 201 is coupled to the computingdevice via the I/O interface 216, such as via a USB port, a Thunderboltport, a FireWire (IEEE 1394) port, and/or any other type serial orparallel data port. In some examples, the test fixture 201 is coupled tothe network interface 214 and/or to the I/O interface 216 via a wired orwireless connection (e.g., Ethernet, Wi-Fi, etc.), either directly orvia the network 218.

The test fixture 201 includes a frame 228, a load cell 230, materialfixtures 236, and a control processor 238. The frame 228 provides rigidstructural support for the other components of the test fixture 201 thatperform the test. The load cell 230 may implement the load cell 120 ofFIG. 1 , and measures force applied to a material under test (e.g., thehinged device 102) by an actuator 246 via grips 248 (e.g., the plates110, 120).

The actuator 246 applies force to the material under test and/or forcesdisplacement of the material under test, while the grips 248 grasp orotherwise couple the material under test to the actuator 246.

Example actuators that may be used to provide force and/or motion of acomponent of the test fixture 201 include electric motors, pneumaticactuators, hydraulic actuators, piezoelectric actuators, relays, and/orswitches. While the example test fixture 201 uses a motor, such as aservo or direct-drive linear motor, other systems may use differenttypes of actuators. For example, hydraulic actuators, pneumaticactuators, and/or any other type of actuator may be used based on therequirements of the system.

The example grips 236 include platens, clamps, and/or other types offixtures, depending on the mechanical property being tested and/or thematerial under test. The grips 236 may be manually configured,controlled via manual input, and/or automatically controlled by thecontrol processor 238.

The test system 100 may further include one or more control panels 250,including one or more input devices 252. The input devices 252 mayinclude buttons, switches, and/or other input devices located on anoperator control panel. For example, the input devices 252 may includebuttons that control the actuator 242 to jog (e.g., position) the grips248 to a desired position, switches (e.g., foot switches) that controlthe grips 248 to close or open (e.g., via another actuator), and/or anyother input devices to control operation of the testing test fixture201.

The example control processor 238 communicates with the computing device202 to, for example, receive test parameters from the computing device202 and/or report measurements and/or other results to the computingdevice 202. For example, the control processor 238 may include one ormore communication or I/O interfaces to enable communication with thecomputing device 202. The control processor 238 may control the actuator246 to move in a given direction and/or to control the speed of theactuator 246, control the fixture(s) 236 to grasp or release a materialunder test, and/or receive measurements from the displacement transducer232, the load cell 230 and/or other transducers.

The example control processor 238 is configured to implement arepetitive motion testing process in which a test specimen (e.g., thehinged device 102) is subjected to testing in the test fixture 201. Forexample, to measure stress on the hinged device 102 during or after aseries of folding and unfolding motions, the control processor 238controls the actuator 246 to move the grips 248 (e.g., the first andsecond plates 110, 112) while monitoring the load cell 230 to measurestress on the hinged device 102. In some examples, the control processor238 monitors a motor encoder of the actuator 246 to determine a foldingangle and/or establish a folding degree-per-pulse ratio.

FIG. 3 is a perspective view of an example implementation of the hingeddevice test system 100 of FIG. 1 . The example view of FIG. 3illustrates the hinges 104 and the first and second portions 106, 108 ofan example hinged device 102 attached to the hinged device test system100. FIG. 3 further illustrates two example drive arms 116 a, 116 bconfigured to move the second plate 112 via corresponding cam followers114 a, 114 b. FIG. 4A is an elevation view of the example hinged devicetest system 100 of FIG. 3 in which the hinged device 102 is in an openedor unfolded position. FIG. 4B is an elevation view of the example hingeddevice test system 100 of FIG. 3 in which the hinged device 102 is in aclosed or folded position.

As illustrated in FIGS. 3, 4A, and 4B, the drive arms 116 a, 116 binclude respective slots 302 a, 302 b extending radially from a pivotaxis 304 of the drive arms 116 a, 116 b. In the example of FIG. 3 , theactuator 118 actuates (e.g., rotates) the drive arms 116 a, 116 via anaxle 306 defining the pivot axis 304. The slots 302 a, 302 b guide therespective cam followers 114 a, 114 b as the drive arms 116 a, 116 arerotated, while permitting the cam followers 114 a, 114 b to move freelyalong the lengths of the slots 302 a, 302 b as the drive arms 116 a, 116b are rotated. The cam followers 114 a, 114 b are coupled to the secondplate 112 via a support axle 314 coupling the cam followers 114 a, 114b.

The example hinged device test system 100 of FIGS. 3, 4A, and 4B limitthe loads from the hinges 104 a, 104 b on the load cell 120 via a hingesupport plates 308 a, 308 b that are coupled to a base plate 310. Duringtesting, the hinge support plates 308 a, 308 b hold respective firstsides of the hinges 104 a, 104 b separately from the first plate 110. Asa result, resistive forces by the hinges 104 a, 104 b created duringfolding and unfolding of the hinged device 102 are transferred to thehinge support plates 308 a, 308 b instead of being transferred to thefirst plate 110 and the load cell 120.

The example translation linkage 122 includes flexures 312 a, 312 b,which are coupled to the base plate 310. The flexures 312 a, 312 bsupport the first plate 110 and permit transfer of load from the hingeddevice 102 to the load cell 120. The flexures limit 312 a, 312 bmovement of the first plate 110 in directions other than the directionin which the load cell 120 measures force.

While the examples disclosed above include the entire hinged device 102,in other examples the hinges 104 a, 104 b may be coupled directly to thefirst and second plates 110, 112, without the first and second portions106, 108 of the hinged device 102. Additionally or alternatively, whiletwo drive arms 116 a, 116 b are illustrated in FIG. 3 , other examplesmay include one drive arm or three or more drive arms.

FIG. 5 is a more detailed view of the example first plate 110, theflexures 312 a, 312 b, and the load cell 120. The example flexures 312a, 312 b are supported by brackets 502 a, 502 b, which are coupled tothe base plate 310.

The flexures 312 a, 312 b include strips of metal attached to thebrackets 502 a, 502 b and the first plate 110 to support the weight ofthe first plate 110. The first plate 110 is also coupled to the loadcell 120 to transfer loads to the load cell 120 for measurement.

To avoid overloading of the load cell 120, the first plate 110 includesa stopping point configured to prevent the first plate 110 fromtraveling toward the load cell 120 beyond the stopping point. In theillustrated example, the stopping point is implemented using stoppingblocks 504 a, 504 b. Support brackets 506 a, 506 b couple the flexures312 a, 312 b to the first plate 110. The blocks 504 a, 504 b areconfigured to stop support brackets 506 a, 506 b that couple theflexures 312 a, 312 b to the first plate 110 after a predeterminedamount of travel of the support brackets 506 a, 506 b (e.g., apredetermined amount of load on the first plate 110).

FIG. 6 is a side elevation view of the example hinged device test system100 of FIG. 3 . FIG. 7 is a plan view of the example hinged device testsystem 100 of FIG. 3 .

FIG. 8 illustrates a partially exploded view of another exampleimplementation of the translation linkage 122 of FIG. 1 . The exampletranslation linkage 122 of FIG. 8 includes a first four-bar linkage 802,a second four-bar linkage 804, and a frame 806. The frame 806 is coupledto be stationary with respect to the base plate 310 (e.g., via the hingesupport plates 308 a, 308 b, or another structure). The frame 806 andthe load cell 120 are stationary with respect to each other.

Inner linkages 808, 810 of the four-bar linkages 802, 804 are coupled tothe first plate 110. Intermediate linkages 812, 814, 816, 818 couple theinner linkages 802, 804 to the frame 806. Similarly to the flexures 312a, 312 b of FIG. 3 , the first and second four-bar linkages 802, 804limit movement of the first plate 110 in directions parallel to thesurface of the first plate 110 on which the first part 106 of the hingeddevice 102 is mounted, while permitting loads from the first plate 110to be transferred to the load cell 120 (e.g., via an extension post 308coupled to the load cell 120) in a direction perpendicular to thesurface of the first plate 110.

The present methods and systems may be realized in hardware, software,and/or a combination of hardware and software. The present methodsand/or systems may be realized in a centralized fashion in at least onecomputing system, or in a distributed fashion where different elementsare spread across several interconnected computing systems. Any kind ofcomputing system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may include a general-purpose computing system with a programor other code that, when being loaded and executed, controls thecomputing system such that it carries out the methods described herein.Another typical implementation may comprise an application specificintegrated circuit or chip. Some implementations may comprise anon-transitory machine-readable (e.g., computer readable) medium (e.g.,FLASH drive, optical disk, magnetic storage disk, or the like) havingstored thereon one or more lines of code executable by a machine,thereby causing the machine to perform processes as described herein. Asused herein, the term “non-transitory machine-readable medium” isdefined to include all types of machine readable storage media and toexclude propagating signals.

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As usedherein, for example, a particular processor and memory may comprise afirst “circuit” when executing a first one or more lines of code and maycomprise a second “circuit” when executing a second one or more lines ofcode. As utilized herein, “and/or” means any one or more of the items inthe list joined by “and/or”. As an example, “x and/or y” means anyelement of the three-element set {(x), (y), (x, y)}. In other words, “xand/or y” means “one or both of x and y”. As another example, “x, y,and/or z” means any element of the seven-element set {(x), (y), (z), (x,y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means“one or more of x, y and z”. As utilized herein, the term “exemplary”means serving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations. Asutilized herein, circuitry is “operable” to perform a function wheneverthe circuitry comprises the necessary hardware and code (if any isnecessary) to perform the function, regardless of whether performance ofthe function is disabled or not enabled (e.g., by a user-configurablesetting, factory trim, etc.).

While the present method and/or system has been described with referenceto certain implementations, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted without departing from the scope of the present methodand/or system. For example, block and/or components of disclosedexamples may be combined, divided, re-arranged, and/or otherwisemodified. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentdisclosure without departing from its scope. Therefore, the presentmethod and/or system are not limited to the particular implementationsdisclosed. Instead, the present method and/or system will include allimplementations falling within the scope of the appended claims, bothliterally and under the doctrine of equivalents.

What is claimed is:
 1. A hinged device testing system, comprising: afirst plate comprising a first surface configured to hold stationary afirst side of a hinged device under test; a second plate comprising asecond surface configured to hold a second side of the hinged deviceunder test; a first cam follower coupled to the second plate; a firstdrive arm configured to move the first cam follower to cause the secondplate to rotate about a hinge pivot axis of the hinged device undertest; an actuator configured to rotate the drive arm; a load cellconfigured to measure loads on the first plate while the actuator movesthe second plate; and a translation linkage configured to limit movementof the first plate in directions parallel to the plane of the firstsurface and permit loads to be transferred from the first plate to theload cell in a direction perpendicular to the plane of the firstsurface.
 2. The hinged device testing system as defined in claim 1,wherein the first plate and the second plate are configured to positionthe hinge of the hinged device under test based on a pivot axis of thedrive arm.
 3. The hinged device testing system as defined in claim 1,wherein the drive arm comprises a slot extending radially from a pivotaxis of the drive arm, and the slot is configured to guide the camfollower as the drive arm is rotated.
 4. The hinged device testingsystem as defined in claim 3, wherein the slot is configured to permitthe cam follower to move freely along the slot as the drive arm isrotated.
 5. The hinged device testing system as defined in claim 1,wherein the second plate is configured to attach the cam follower atmultiple positions on the second plate.
 6. The hinged device testingsystem as defined in claim 1, wherein the translation linkage comprises:a frame that is fixed with respect to the load cell; and a firstfour-bar linkage coupled to the frame and the first plate.
 7. The hingeddevice testing system as defined in claim 6, wherein the translationlinkage further comprises a second four-bar linkage coupled to the frameand the first plate.
 8. The hinged device testing system as defined inclaim 1, wherein the translation linkage comprises a flexure configuredto support the first plate and to permit transfer of load from thehinged device under test to the load cell.
 9. The hinged device testingsystem as defined in claim 1, further comprising control circuitryconfigured to control the actuator to move the second plate in a firstdirection to fold the hinged device under test or in a second directionto unfold the hinged device under test.
 10. The hinged device testingsystem as defined in claim 1, further comprising a hinge support plateconfigured to hold a first side of the hinge separately from the firstplate.
 11. The hinged device testing system as defined in claim 10,wherein the second plate is configured to hold the second side of thehinge, such that the hinge controls a folding path of the hinged deviceunder test as the actuator moves the second plate.
 12. The hinged devicetesting system as defined in claim 10, wherein the hinge support plate,the second plate, the first plate, the drive arm, and the cam followerare configured to limit forces on the load cell to forces of the hingeddevice under test during folding and unfolding without forces created bythe hinge during the folding and unfolding.
 13. The hinged devicetesting system as defined in claim 1, wherein the translation linkagecomprises a plurality of parallel flexures configured to support thefirst plate and to permit transfer of load from the hinged device undertest to the load cell.